Edge-enriched CeO2/MoS2 heterostructure with coupled interface for enabling selective room-temperature NO2 detection

Endowed with abundant oxygen vacancy and excellent redox properties, CeO2 has attracted extensive attention for potential application in gas sensing, while it suffers from high working temperature and low sensing response. Herein, the MoS2 nanoflowers with abundant edges are coupled with CeO2 nanoparticles and the edge-enriched heterostructure is formed at interface. Owing to the synergistic effects of strong adsorption, abundant adsorption sites, and coupled interface, the CeO2/MoS2 compounds behave excellent room-temperature NO2 sensing performance. The 5 ppm NO2-sensing response of compounds is enhanced by 1033% and 450% in company with pure CeO2 and MoS2, respectively and the low detection limit of 1 ppm, high recovery rate, excellent long-term stability and selectivity are also obtained at room temperature. According to first-principles calculation, the binding energy of CeO2 for NO2 is much more negative than that of MoS2. Functionalization of MoS2 with CeO2 substantially improves NO2 adsorption. The Fermi level of MoS2 is nearer to the vacuum level than that of CeO2. The electrons are transferred from MoS2 to CeO2 at interface to create an electric field and an electron accumulation layer is formed on CeO2 to promote electron exchange between NO2 and the sensor and the NO2sensing response. The results promote the application of two-dimensional materials to gas sensing boding well for the wireless sensing systems development in environmental and safety monitoring.